Plastic duplicate of cellulosic or proteinaceous material, article or object

ABSTRACT

A plastic, material, article or object formed as a substantial duplicate in high molecular weight polymeric material such as polyfluorocarbon resins, polyvinyl chloride and polyvinyidene chloride; of a matrix consisting of cellulosic and proteinacious materials by the process of impregnating a selected matrex with the selected high molecular weight polymeric material and carbonizing the matrix in a controlled concentration of oxygen at a temperature at least equal to the sintering temperature of the selected high molecular weight polymeric duplicating material until the duplicating material coalesces to form the selfsupporting continuous duplicate by gradual replacement of the carbonizing fibers of the selected matrix.

States Pate Rosenblatt Nov. 27, 1973 [54] PLASTIC DUPLICATE OFCELLULOSIC OR 2,568,883 2/1952 Stroh 260/2.l E X PROTEHNACEOUS MATERIAL,ARTICLE 3,056,686 10/1962 Shannon 260/2.l R X 2,977,265 3/1961 Forsberget a1... [61/50 X 0R OBJECT 2,825,706 3/1958 Sanders 117/161 UP [75]Inventor: Solomon Rosenblatt, Nutley, NJ. 3,047,421 7/1962 Taylor117/161 UP ['73] Assignee: Chemplast, Inc., East Newark, NJ. FOREIGNPATENTS OR APPLICATIONS 22 Filed: June 25 971 666,361 7/1963 Canadall7/l38.8 UF

21 Appl. No.: 157,001

Related US. Application Data [52] U.S. Cl....1l7/138.8 VA, 117/46 CC,ll7/l38.8

UF, 117/141, 117/143 A, 117/161 UP, 128/ Primary ExaminerRalph HusackAtt0rney-Daniel H. Bobis [5 7] ABSTRACT A plastic, material, article orobject formed as a sub stantial duplicate in high molecular weightpolymeric material such as polyfluorocarbon resins, polyvinyl chlorideand polyvinyidene chloride; of a matrix consisting of cellulosic andproteinacious materials by the process of impregnating a selected matrexwith the selected high molecular weight polymeric material andcarbonizing the matrix in a controlled concentration of oxygen at atemperature at least equal to the sintering temperature of the selectedhigh molecular weight polymeric duplicating material until theduplicating material coalesces to form the self-supporting continuousduplicate by gradual replacement of the carbonizing fibers of theselected matrix.

7 Claims, 10 Drawing Figures [51] Int. Cl. B41m 5/24, B29c 13/00 [58]Field of Search 264/49, 127, 44, 264/317, 126; 260/41 A, 2.1 R, 2.5 M;117/161 UF, 138.8 UP, 46 CC; 161/46 [56] References Cited UNITED STATESPATENTS 2,773,781 12/1956 'Rodman 117/l38.8 UF 3,090,094 5/1963Schwartzwalder et al 264/44 X 2,838,045 6/1958 Ryznar 117/161UF 3 t 45a. COLLOIDAL DISPERSION MATRIX DRYl G OVEN HEAT S\NTER|NG FURNACEFURNACE OXIDIZING SOLUTION NEUTRALIZING TANK PLASTIC DUPL PATENTEDNGV 27I975 SHEET 1 BF 3 i.2 s mms lMPREGNAm TISSUE PAPER ig. I E PAPER SAMPLETISSU l-|g.4 A C DUPLICATE SINTERED SAMPLE INVENTOR SOLOMON ROSENBLATTATTORNEY PMENIEUnuv 27 1913 SEJFFT P, RF

9 SOLOMON ROSENBLATT PLASTIC DUPLICATE OF CELLULOSIC OR PROTEINACEOUSMATERIAL, ARTICLE OR OBJECT This application is a continuation ofco-pending application Ser. No. 870,994 filed Sept. 2, 1969 which lastmentioned application was a division of application Ser. No. 433,631filed Feb. 18, 1965. Application 870,994 will become abandoned after theeffective filing date of the present application and application Ser.No. 433,631 has matured into US. Pat. No. 3,497,256 granted Feb. 24,1970.

BACKGROUND OF THE INVENTION Various methods of making plastic filaments,plastic sheets and plastic articles are known in the prior art. Forexample, it is known to form plastic paper by the deposition of plasticfibers, a technique which duplicates for the most part the proceduresfor making paper. Similarly techniques have been developed for weavingplastic filaments similar to the procedures used for making cloth.

It is also known that replicas of the gross appearance of objects,articles and materials made of certain expanded solids such aspolyurethane; polystyrene and urea-formaldehyde foams and sponges can beeffected by impregnations of such objects with slurries and then curingthe impregnated object or article as is set forth in US. Pat. Nos.3,111,396 and 2,805,208; and replicas of cellulose fibers has also beenachieved by an encapsulating technique as described in US. Pat. No.3,121,698.

However these last mentioned procedures cannot and do not reproduce inall the fine detail substantially the exact internal and external fibergeometry of objects, articles and sheets of material and thereforecannot duplicate in such replicas the properties and qualities of thesereproduced objects, articles and sheets of material.

The present invention seeks to overcome the problems incident toapplying our modern day materials to the old techniques for makingpaper, textiles, and other types of objects, articles and materials; andthe problems of earlier efforts to reproduce copies of such objects,articles and materials; by providing a novel direct conversionduplication process for making in plastic, sheets, objects, articles andfilaments from counterpart, sheets, objects, articles and filaments ofless thermally stable or chemically stable matrices.

In the present invention the object, article, sheet of material orfilament selected to be duplicated will have a given carbonization rangeand will provide the internal and external form or geometry of a matrixor model to be impregnated which fine particles of a duplicatingsubstance, related to the matrix in that its sintering temperature iswithin the carbonization range of the matrix; the particles duringimpregnation being randomly deposited so that when the impregnatedmatrix is subject to temperatures at or above the point of carbonizationin a controlled atmosphere, continuous and controlled carbonization anduniform sintering can be effected to cause the particles of theduplicating substance to orient and coalesce in and along the fibers ofthe fiber geometry of the matrix and thus provide a substantialduplicate of the internal and external fiber geometry of the originalmatrix in the duplicating substance which if necessary can be furthertreated to remove any residue of the original matrix.

The term matrix when used herein shall mean any filament, material,object or article which can be decomposed or eliminated by heat orelevated temperatures or by chemical processes and/ or other techniqueswhich do not simultaneously affect and damage the duplicating substanceand is capable of maintaining its geometry under the processing stepsand conditions necessary to establish the duplicate counterpart.

In the present invention the duplicating substances referred to hereinand illustrated as the material deposited and impregnated into andthroughout the fiber structure of a matrix or model to be duplicated areplastics and when used herein plastic or plastics are intended to meanhigh molecular weight polymeric materials or compounds most of which arenot known to exist in natural form such as polytetrafluoroethylene;polymonochlortrifluoroethylene, polyvinylchloride,polyvinylidenechlon'de, etc; and further while plastics are used in theexamples set forth below it will be clear to those skilled in the art asis more clearly described below that any substance can be utilized whichhas the properties to act relative to the matrix according to the stepsof the present process and further can be deposited in the concentrationand particle sizes to effect the required infiltration and impregnationof the fibers of the matrix to be duplicated can be utilized to achievethe advantageous results of the present invention.

Accordingly it is an object of the present invention to make plasticsheets of material and plastic objects, filaments and articles by thedirect conversion and duplication of a less chemically or thermallystable matrix.

It is another object of the present invention to reproduce a matrixpreferably one that is porous in a material which is superior to thematrix without going through the fundamental processes by which thematrix was produced or fabricated.

It is an object of the present invention to make or form materials,objects, filaments and articles made of plastic and other materialshaving more superior qualities and fundamental advantages than similararticles of less superior material which serve a variety of similar ornew uses such as chemically resistant filters for solutions and gases;sterilizable non-sticking medical dressings; heart and lung machinemembranes and dialysis membranes for artificial kidneys; porousnon-woven plastic fabrics; battery separators; porous textile fabrics;lint-free wipers; non-wettable plastic paper; and special products forinsulation and for uses where the less superior materials tend to breakdown or fail to function.

With these and other objects in view the invention may be betterunderstood by reference to the accompanying drawing on which:

FIG. 1 is a representation of a photomicrograph at a magnification ofabout 200 diameters of a control sample of a conventional piece oftissue paper. The fibers shown in the tissue paper control sample areabout 550 microns in length, and about 25-40 microns in diameter.

FIG. 2 is a representation of a photomicrograph on the same scale asFIG. 1 of the same kind of tissue paper impregnated with a deposit of afine dispersion of a polyfluorocarbon resin by the procedure describedin Example 2.

FIG. 3 is a representation of a photomicrograph on the same scale asFIG. 1 of a charred piece of the coextensive tissue paper control samplewith its deposit of polyfluorocarbon resins of FIG. 2.

FIG. 4 is a representation of a photomicrograph on the same scale asFIG. 1 of the pure polyflurorcarbon resin duplicate of the controlsample of tissue paper made according to the method of Example 2.

FIG. 5 is a diagrammatic perspective view of an enlarged portion of thefiber matrix of a control sample of conventional tissue paper after thefinely divided particle of a deposited substance has infiltrated andimpregnated the fiber matrix of the tissue paper and illustrates thediscontinuous phase of the present invention.

FIG. 6 is a cross section taken on line 66 of FIG.

FIG. 7 is a diagrammatic perspective illustration of the enlargedportion of the fiber matrix of FIG. 5 after the deposited substance hasbeen sintered and illustrates the continuous phase of the plasticduplicate as being 25 percent smaller in volume than the original fibermatrix of the tissue paper sample.

FIG. 8 is a cross section taken on line 88 of FIG.

FIG. 9 is a diagrammatic perspective illustration of the enlargedportion of the sintered plastic duplicate of FIG. 7 after it has beenoxidized.

FIG. 10 is a diagrammatic illustration of one form of apparatus toaccomplish the method of the present invention.

Broadly the process of the present invention relies on an interrelationbetween the properties of the duplicating substance and the propertiesof the less chemically and thermally stable material of the matrix suchthat when the steps of the process hereinafter described are followedthere is formed in the duplicating substance an identical duplicatestructure of the matrix; duplication occurring as a function of thecontrolled elimination of the matrix.

Duplicating substances which meet these requirements are those which canbe formed in the concentration and particle size to permit theduplicating substance to be infiltrated and impregnated throughout theinternal and external fiber geometry of a matrix to be duplicated;sinter or coalesce and are stable at the carbonization temperature andconditions to which the matrix being duplicated is subjected; and havesufficient mobility at the carbonization temperature and under thecontrolled atmosphere to which the matrix is subjected to orient so asto replace and substitute for the actual structure of the fiber geometryof the matrix as the matrix is slowly decomposed and shrunk due tooxidation at the carbonization conditions to which it is subjected.

Conversely the matrix of the present process must be one whichcarbonizes within a temperature range which includes the criticalsintering temperature of the duplicating substance; and when subjectedto carbonization maintains the internal structure of the fibers for asufficient length of time, as for example, in the formation of acarbonaceous skeleton of the fibers of the matrix to produce duringcarbonization sufiicient local heat of combustion at the discrete fibersthat the surface tension of the randomly deposited particles of theduplicating substance in, on, into and along these fibers issufficiently lowered with respect to the particles between the fibersthat all the particles gradually align, orient and coalescepreferentially in, on, into and along the fibers and thus formsubstantial duplicates of the entire fiber geometry of the matrix.

The preferred impregnating substances used for duplicating the matrixare colloidal dispersions of polyfluorocarbon resins, such aspolytetrafluoroethylene, in combination with a suitable wetting agentfor reasons which are set forth more fully below. However, theimpregnating substances need not be limited to acqueous colloidaldispersions but may be any suitable vehicle which can carry the requiredconcentration and particle size of the duplicating substance required inthis process. Thus, an organic suspension of monochlorotrifluoroethylenewill work equally as well as does latices,

etc., and powdered or crystalline solids of a symbiotic W duplicatingsubstance may also be used where the technique for effectinginfiltration and impregnating of the fiber geometry of the matrix can bevaried as by vacuum deposition or sublimation techniques.

Acqueous colloidal dispersions of polyfluorocarbon resin in combinationwith wetting agents are preferred because they are available in the openmarket; the surface energy between the continuous phase of a colloidaldispersion the colloid in the dispersion and a fiber on which thecolloid dispersion is deposited may be widely modified by the type andconcentration of the wetting agent to take advantage of the processes ofsurface chemistry for optimum infiltration and impregnation of the fibergeometry of the matrix, and they provide the concentration and particlesize for a given duplicating substance as will appear clear from theexample of the process hereinafter illustrated to develop the internaland external surface detail of the fiber geometry of the preselectedmatrix. By the correct choice of wetting agent one may simultaneouslyenhance colloid stability and decrease the surface tension of thecontinuous phase of the colloidal dispersion so that the continuousphase of the colloidal dispersion will infiltrate and impregnate thefiber geometry of the matrix carrying with it and thus spreading theparticles of colloid evenly on, into and throughout the internal andexternal surfaces and interstital spaces of the fiber geometry of thematrix with a minimum of bridging between interlaced and unconnecteddiscrete fibers.

In the present invention particle size must be correlated with themobility of the duplicating substance selected. Mobility being thatproperty at the carbonization and sintering conditions which causes theparticles of the duplicating substance to spread in the area of thefiber on which it is deposited beyond the initial peripheral boundariesof the original solid state condition of the deposited particle.

When the mobility of the duplicating substance is high under theconcurrent carbonization and sintering conditions a larger particle sizemay be used and where mobility is low a smaller particle size will beused.

Thus, in the examples of the process hereinafter set forth where theparticle size of the colloidal dispersion is in a range from 0.1 to 0.5microns, this is only by way of illustration for the type of colloidselected and the matrix being duplicated.

These fluid dispersions of the examples of the process set forth belowhave a mobility such that their particle size is sufficiently small andthe concentration proper to faithfully develop the internal and externaldetail of the selected matrices such as cellulose paper, cotton cloth,etc, where the discrete fibers have a length of 500 microns and adiameter of 20-50 microns, a size almost gigantic in relative comparisonto the particle size of the deposited colloid.

In either instance whether the mobility of the duplieating substance ishigh or low, concentration is adjusted to provide the degree of faithfulduplication of the fiber geometry of the matrix desired.

As a rule, concentrations of percent by volume of the colloid in acolloidal dispersion with a particle size between 0.1 to 0.5 micronswill work favorably on 75 percent of the matrices to be duplicated. Ithas been found at this concentration that the thickness of the duplicatestructure in the plastic or other duplicating substance is approximatelyequal to the matrix or model being duplicated. V

Colloid concentration is best evaluated by microscopic examination ofthe duplicate structure.

If microscopic examination of the plastic duplicate reveals excesses ofthe duplicating substances on the surfaces and in the pores between thefibers of the duplicate structure, and in other ways lacks fidelity whencompared to the original matrix, then by reducing the concentration ofthe colloid in the colloidal dispersion one may obtain the desiredconcentration to produce a sharp and faithful replica of the originalmatrix or model.

Conversely, if microscopic examination shows exces sive shrinkage andweakness in structure, then the concentration of the colloid in thecolloidal dispersion must be increased.

A proper combination of colloidal dispersion and wetting agent is onewhich enhances colloid particle stability, increases the flow propertiesof the continuous phase of the colloidal dispersion and increases thecapillary action of the continuous phase of the colloidal dispersioninto the fiber geometry of the matrix so that the colloid will bedeposited by the colloidal dispersion homogeneously in, on, into andthroughout the fiber geometry of the matrix.

A surfactant (wetting agent) such as Triton X 100 (Rohm and Haas) or ofthe class of polyethylene oxide (alkyl) phenol ethers, non-ionic wettingagents in a range between 0.2 percent and 10 percent by weight of thecolloidal dispersions has been used effectively as is clear from theexamples set forth below.

By the proper combination of colloid and wetting agent it has been foundthat the duplicated structure in the deposited duplicating substanceswill duplicate faithfully even to the point that joining will not occurbetween contacting but unconnected interlaced fibers of the originalmatrix being duplicated. The duplicate structure is found to have thesame discrete fibers in the duplicated substances as existed in thematrix.

Where an organic suspension is used as the vehicle for the finelydivided duplicating substance the solvent used will act to provide thedesired stability of the particle of the substance and provide thedesired surface tension of the continuous phase for the organicsuspensoid to produce the same results obtained by the acqueoussolloidal dispersion and wetting agents.

GENERAL STEPS IMPREGNATING STEP:

Thus, in the present invention a matrix to be duplicated either infilament, sheet, object, or article form having the properties above setforth must first be selected. Materials, objects, articles and filamentsmade of cellulose, regenerated rayon, wool and the like materialsillustrate matrices which fulfill these requirements.

Next an impregnating substance is selected in which to duplicate thematrix having the desired relation with this matrix at the carbonizationtemperature for the matrix and the necessary properties to effectinfiltration and impregnation of the matrix.

The selected matrix is disposed so that it can be infiltrated andimpregnated by the random deposition of a fine dispersion of theduplicating substance and this may be accomplished by any suitabletechnique.

If colloidal dispersions; organic suspensoids; latices, etc., are usedas the component vehicles for the duplicating substance, thedispersions, suspensions, etc., may be deposited in, on, into, andthroughout the fiber geometry of the matrix by spraying, dipping,rolling or by spreading as with a squeegee.

If the duplicating substance is in powder or crystalline formimpregnation can be effected by vacuum deposition or other sublimationtechnique.

Any and all of these deposition techniques may be used alone or incombination, with the object, that the front, back, side ends, crevices,fissures, etc., on each fiber and in, into and about the internal andexternal surfaces of the fibers of the matrix and many of theinterstitial spaces between the fibers will have randomly depositedthereon discrete particles of the colloid carried by the continuousphase of the dispersion or suspension.

This step or condition of the process is more readily understood byreference to FIGS. 1, 2, 5, and 6 of the drawings.

FIG. l shows microscopically the fiber geometry of a sample ofconventional tissue paper befofe it has been impregnated by theduplicating substance. Note that the voids or interstitial spacesbetween the fibers of the matrix and the fiber construction itself isclear and well defined. Contrast this with the microscopic examinationof the structure shown in FIG. 2.

FIG. 2 shows the tissue paper sample impregnated with a duplicatingsubstance in accordance with Example 2 hereinafter set forth. In thisfigure the fibers are now visible but blurred because of the presence ofthe translucent deposits of the plastic impregnating or duplicatingsubstance in, on, about, or throughout to fibers of the tissue papersample.

At FIGS. 5 and 6, a diagrammatic illustration of an enlarged section ofthe tissue paper sample generally designated 1 shows a few fibers 2 withthe deposit of discrete particles as at 3 of the plastic duplicatingsubstances. At least one of the interstitial spaces as at 4 is filledwith the deposited discrete particles of the duplicating substances asare the crevices 5 and fissures 6.

As was pointed out, the relative size of the particles of theduplicating substance is an important factor in effecting theadvantageous results of the present invention and the diagrammaticsketched attempt to show that the size of the particles is about O.l to0.5 micron while the fibers are in a range of from 500 microns in lengthand 20 to 45 microns in diameter.

The impregnated matrix must now be put through a series of steps toeliminate the matrix and fully develop the substantial duplicate thereofin the duplicating substance with which it is impregnated.

Drying Steps:

If the duplicating substance deposited on the matrix with a so] or asolvent the impregnated matrix must be dried or the solvents evaporatedso that only the discrete particles of the duplicating substance remainon the fibers of the matrix, and it will be recognized by those skilledin the art that regardless of the method of random disposition selectedthe final positions of the discrete particles will form from particlesto particles a discontinuous film of the duplicating substance in, on,into and throughout the fiber geometry of the matrix.

Slow drying is preferred to prevent the formation of pits, flaws, scarsor distortion of the surface of the duplicated fiber structure in thefinished product and the drying process in effect is a slow modulationor change in two stages to the desired final condition where the sol orsolvent has been dissipated.

In the first stage, for example, as drying of the colloid dispersionprogresses a certain amount of the continuous phase, i.e. the water,will be driven off until at a certain concentration, the colloid, whichis the true duplicating substance, will precipitate into its positionrelative to the fiber geometry of the matrix. After this occurs theremaining portion of the continuous phase of the colloid, the remainingwater, can be driven off at a more rapid rate.

The final result to be achieved from the drying step is the matriximpregnated with only the discrete particles of finely dividedduplicating substance.

This drying step can be accomplished by air drying (in a 150Frecirculating air oven) or by controlled infra red radiation.

Drying time will of course vary with the complexity and thickness of thematrix being dried.

When the impregnated matrix is fully dried the coextensive unit is readyfor the steps of the process which will change the discontinuous film ofthe duplicating substance into an integral unit or continuous film ofthe duplicating substance from which the substantial duplicate of thematrix in the pure duplicating substance is established.

CARBONIZATION AND SINTERING If the fiber geometry of th matrix has beenimpregnated with the proper concentration and particle size for theparticular duplicating substance then because of the preselectedproperties of the matrix and the duplicating substance wherein thecritical sintering temperature of the duplicating substance is wellwithin the range of carbonization temperatures for the matrix; a gradualduplication of the matrix in the duplicating substance can beestablished or effected by simultaneous or concurrent controlledcarbonization of the matrix on the one hand and sintering of theduplicating substance on the other.

Controlled carbonization of the matrix along with the advantageouschanges in the surface energy of the particles of the depositedduplicating substance are key factors which regulate the extent of theformation of the duplicating substance into a faithful duplicate of thematrix.

The nature of the relation of the particle size and mobility of theparticular duplicating substance selected on being raised to thesintering temperature as well as the effect of concentration to give thedesired faithful duplicate has been considered above.

Controlled carbonization is effected by regulating the oxidation rate ofthe matrix through the various stages of the formation of itscarbonaceous skeleton and controlled shrinkage and partial eliminationof the skeleton as the concurrent steps of carbonization and sinteringprogress to produce the desired duplicate.

Broadly one result of the controlled carbonization conditions is toeffect continuous local heat of combus tion in the fiber geometry of thematrix to raise the tem perature of the particles of the duplicatingsubstance deposited in, on, into and along the discrete fibers abovetheir critical sintering temperature thus causing the surface tension ofthese particles to become relatively lower than those between thefibers, increase their mobility and the movement of those particlesbetween the fibers so that all the particles of the duplicatingsubstance align, orient and coalesce in, on and along the internal andexternal surfaces of the discrete fibers to form a continuous unit, aduplicate of each fiber and hence that of the entire fiber geometry ofthe matrix.

Further, however, carbonization is preferably conducted under conditionswhere the rate of oxidation of the matrix is controlled in order toregulate the shrinkage of the matrix that is the reduction in volume ofthe fiber geometry of the matrix.

Shrinkage is desirable because it helps to increase the mobility of thedeposited particles of the duplicating substance and thus it not onlyaids coalescing of the particles, but further increases the capacity ofthe particle to align and orient and as they coalesce in, on, into andalong the fibers to replace or fill in the space left by the products ofcombustion formed during oxidation of the matrix and escaping betweenthe coalescing particles of the duplicating substance.

Shrinkage is a function of the oxygen present during carbonization andis controlled by regulating the conditions of the atmosphere under whichsintering is being effected. If the system is adjusted to recirculateapproximately -70 percent of the hot air containing the gases ofcombustion and make up air in a range between 30 to 40 percent is addedto the recirculated air an approximate overall shrinkage rate of 25percent of the matrix will result. It has been found that whencarbonization and the sintering schedule are controlled so thatshrinkage is limited to about 25 percent of the overall area and volumeof the original matrix that a relatively faithful duplicate of thediscrete fibers and the overall fiber geometry of the matrix with goodstrength is obtained in the duplicating substance.

For example, for carbonization of a square yard of impregnated paper ina one cubic foot oven enough make up air is introduced to have at leastone complete air change every minute. The mass of impregnated matrixwill control the required quantities of oxygen that will have to bepresent to produce the desired shrinkage in the present process.

Generally for sintering time, the thinner the matrix the shorter thesintering period and vice versa for a thicker matrix.

The factors that affect and produce a weak structure in the duplicatingsubstance are therefore clear.

a. Under sintering due to low temperature on improper timing producesinsufficient coalescing of the duplicating substance,

b. Proper sintering time and temperature but insufficient controlledcarbonization will produce a weak structure because insufficientshrinkage will not permit the advantageous orientation and migrationrequired to produce the desired continuous development of an integralunit in the duplicating substance.

Conversely excess sintering time, higher temperatures, not beyond thedecomposition point of the duplicating substance, and increased oxygencan be used to increase shrinkage where it is desired to make a lessporous duplicate structure.

Thus under atmospheric conditions, the dried impregnated matrix issubjected to an elevated temperature either at or above that temperaturewhere carbonization of the fiber geometry of the matrix will occur.

So long as there is sufficient oxygen present and the temperature towhich the matrix is subjected is above its carbonization temperature thefiber geometry thereof will undergo combustion and at the discretefibers a local heat of combustion 'will be established which is abovethe critical temperature of the deposited particles of the duplicatingsubstance, thus causing these particles to align and orient and tocoalesce in, on and along all the internal and external surfaces of thediscrete fibers on which the particles are deposited, and form thesubstantial duplicate of the matrix in the duplicating substance.

As carbonization of the fiber geometry of the matrix progresses, thecarbonaceous skeleton forms combustion products which escape in the formof a gas between the coalescing particles of the duplicating substanceand thus the fibers and the overall volume of the matrix to shrink underthe oxidation conditions of the present process.

The function and effect of shrinkage as above set forth is to increasemobility of the particle of the duplicating substance and aid theparticles to align and orient along the fibers.

Further under the effect of the sintering temperature not only do theparticles coalesce but they fill in the voids left by the escapingproducts of combustion, however because this concurrent step is agradual one and the characteristic initial stage dependant on a strongcarbonaceous skeleton, there is gradual increase in the integrity of theparticles of the duplicating substance as they coalesce into theircontinuous form and a coincident decrease in the form and structure ofthe discrete fibers on which the particles were deposited.

In order to speed up concurrent carbonization and sintering it has beenfound generally desirable to subject the impregnated matrix to anambient temperature at least equal to but preferably higher than thecritical sintering temperature for the duplicating substance. However,it will be understood that lower temperatures as well as highertemperatures can be used and carbonization controlled by varying therate of oxidation as may be required by the particular conditions forany given impregnated matrix.

An elevated temperature of about 50F higher than the critical sinteringtemperature for the duplicating substance is generally used in thisconcurrent carbonization and sintering steps of the present processbecause as coalescing of the duplicating substance causes a morecontinuous unitary structure to form it will slowly act to occludeoxygen from reacting with the discrete fibers of the matrix or theremaining portion of the carbonaceous skeleton that have not undergonecombustion and therefore a higher temperature is required to effectoutgoing of the products of combustion.

The Sintering and Carbonization leave a homogeneous deposition ofcarbonaceous ash throughout the now integral and continuous unit of theduplicated matrix now formed of the duplicating substance.

In order to better understand this step, reference will be made to FIGS.3, 7 and 8 of the drawings in which a sintered sample of an impregnatedtissue paper matrix is illustrated.

In FIG. 3, the pigment like particles of carbon appear clearly on thesurface of the individual fibers of the plastic matrix formed from theduplicating substance. However, of even greater significance is that thevoids or intersititial spaces between the fiber are now clearly definedand have increased in number as compared with the same spaces of theimpregnated tissue paper shown in FIG. 2. V

The increase in the interstitial spaces came about as a result of thecombined acts of aligning; orienting along the fibers and sintering orcoalescing which occurs to the discrete particles of the depositedduplicating substance.

In FIGS. 7 and 8, a diagrammatic illustration was made to show how theenlarged section of impregnated fiber matrix of FIG. 5 would look afterthe concurrent steps of sintering and carbonization have been completedand the fibers 10 in these fibers are now duplicates geometrically inthe duplicated substance but slightly smaller in volume and havehomogeneously disposed thereon and therethrough carbon particles 11 ofvarious sizes. The interstitial space 12 between these duplicate fibershowever is now clean and sharp to show the orientation of the particlesthat occured with the sintering and carbonization step which causes themto migrate and form somewhat smaller but geometric equivalents of theoriginal fiber.

The carbonaceous residue of the matrix which is present in the duplicatestructure made of the duplicating substance can now be removed by anysuitable type of oxidation-reduction procedure to provide a duplicate inthe pure duplicating substance. The availability of the particles of thecarbon residue to oxidizers is made possible by the blowing out ofminute passages by the gases of combustion from the carbonizing of thefibers of the matrix to form passage by which the oxidant maysubsequently enter.

OXIDATION-REDUCTION STEP Such oxidation-reduction steps can beaccomplished by passing hot air over the sintered product; by refluxingin nitric acid (HNO and/or Hydrogen peroxide (H 0 by refluxing in aquaregia (I-ICL/I-INO at an elevated temperature; by refluxing 1N HNO (fivemin utes to two hours) and then bleaching in 30-35 percent HydrogenPeroxide five minutes to two hours and or 5-15 percent sodiumhypochlorite or combinations of both.

The sintered and oxidized duplictate is then hydrolyzed and washed indistilled water until it is free of acid and then dried as by hot air orevaporation at room temperature to give the finished duplicate in theduplicating substance.

In FIGS. 4 and 9 of the drawings the final product is shown whereinhomogeneously disposed carbon residue have been oxidized to leave thepure duplicate in the duplicating substance.

The fibers in FIG. 9 are fibers shown in FIG. 7 after they have been putthrough the oxidation-reduction step, and are clearly smaller in size bysome 25 percent.

It is significant to note particularly by comparison with FIGS. 1 and 4of the drawings that the original matrix and the duplicate matrix in theduplicating substance bear such close resemblance to each other that itis difficult to detect significant difference. Even the discrete fibersin the duplicate are clearly distinguishable relative to each other.

Examples of specific matrices duplicated by the general step of thepresent process are as follows:

EXAMPLE 1 Porous non-woven polyfluorocarbon resin duplicate of a matrixof woven cloth material.

A percent by volume colloidal dispersion of polyfluorocarbon resin TFE30 (Dupont TM) (average particle size 0.2 micron) containing 2 percentTRITON X 100 wetting agent was prepared and a cotton bed sheet wasdipped into the colloidal dispersion until the bed sheet was fullysaturated.

The cotton bed sheet was then stretched and dried at room temperatureand was found to be impregnated with a flaky deposit of polyfluorocarbonresin.

The impregnated cotton bed sheet was placed in a suitable sliding frameto allow for shrinkage and the impregnated cotton bed sheet and framewere placed in a controlled oxygen 670F recirculating forced air ovenfor about 20 minutes.

The product removed from the oven was integral and covered with fineparticles of carbon which gave it a blackened appearance.

The blackened product from the sintering over was cooled and then placedin a reflux assembly of 63 percent HNO and allowed to reflux for 16hours at l 15C until all the carbon was oxidized and the characteristicpure white polyfluorocarbon resin counterpart was developed. Thematerial was removed from the reflux assembly and washed in a diluteammonia solution followed by distilled water and then dried in a forcedair over form 10 minutes at 250F.

The final product had all the characteristics of sinteredpolytetrafluoroethylene and was structurally a duplicate of the cottonbed sheet except for size. The plastic duplicate was about percentsmaller in area.

Specific gravity tests on samples of this final product gave a specificgravity of 2.2 which is the specific gravity of polytetrafluoroethyleneand proved the absence of occluded gases.

EXAMPLE 2 POLYFLUOROCARBON RESIN DUPLICATION OF MATRIX OF PAPER PULP Apercent by volume colloidal dispersion of polyfluorocarbon resin 41BX(Dupont TM) and (Dupont TM) (average particle size 0.2 micron)containing 4 percent TRITON X 100 wetting agent was prepared.

A tea bag made of Philippine hemp fibers was dipped into this colloidaldispersion and dried in an oven, at 150F.

The impregnated tea bag had a flaky coating of polytetrafluoroethylene.

The impregnated tea bag was placed between two stainless steel screensand locked in position in such a manner that the top screen did not reston the paper and the entire assembly of frame and plastic impregnatedtea bag was placed in a controlled oxygen 670F recirculating forced airoven for 10 minutes, at which time the product formed was integral andcovered with the characteristic particles of carbon residue which giveit a blackened appearance.

The tea bag was removed from the oven and placed in a reflux assemblyhaving 63 percent on one normal Nitric Acid therein and the tea bag wasallowed to reflux for six hours at l 15C at which time the tea bagturned from black to yellow. I

The tea bag was then placed in a second reflux assembly containing 3335percent Hydrogen Poroxide and allowed to soak at 60 C until thecharacteristic white color of the polyfluorocarbon resin wasestablished.

The plastic counterpart was then dried in a 250F forced air oven and itsspecific gravity tested to confirm that the final product was theolyfluorocarbon resin.

EXAMPLE 3 Polyfluorocarbon Resin Duplication of a three dimensionalMatrix of paper pulp material A paper thimble made of filter paper pulp(Sohxlet extractor thimble) was selected. The thimble was dipped into a20 percent polytetrafluoroethylene dispersion containing 2 percentTRITON X100, and the dispersion was allowed to soak well into thestructure. The thimble was dried by standing it on a metal grid placedover a pan into which a stream of compressed air was being pumped at 4PS1. After drying overnight, the thimble was placed in a C oven for fourhours.

The impregnated thimble was then placed on a porous metal frame which is25 percent less in volume than the thimble but identical in shape, andframe, and the thimble was then placed in a container which has helosdrilled both on the bottom and top.

Container frame and thimble assembly was placed in a 670F oven for 35minutes and then removed from the oven. Then only the frame with thethimble was placed back in the oven for 15 minutes more at 670F, and theframe and thimble was then removed from the frame, cooled and placed ina reflux assembly and refluxed in 63 percent nitric acid for 16 hours at115C, followed by warming for four hours in 3035 percent HydrogenPeroxide at 60-80C until the characteristic white color of thepolyfluorocarbon resin appeared. On test the specific gravity of 2.2 wasobtained.

EXAMPLE 4 Polyfluorocarbon Resin Duplicate of a Matrix of CommercialTissue Paper A sheet of commercial tissue paper (Kimberly ClarksKimwipes) was saturated by a 35 percent colloidal solution, by weight,of a polyfluorocarbon resin dispersion containing 9 percent TRITON X 100(Rohm & Haas).

The particle size range of the dispersion (Duponts TFE3120) did notexceed 0.2 rnicron The paper was treated by causing the dispersion toenter the fibers by capillary action.

The wet impregnated sheet of tissue paper was dried by suspension in a Fair circulating oven for 30 minutes.

The. dried impregnated sheet of tissue paper was then installed in asuitable jig fabricated of flat metal screen where the sheet is heldlightly but taut along the edges in order that shrinkage and sliding maytake place uniformly during the carbonizing process. This was readilydone by forming troughs around the periphery of the screen and usingsmall steel balls as clamps to hold the edges of the paper in thetrough.

Then the jig was placed in a 670F muffle furnace, door slightly ajar,for 12 minutes and sample was removed from the furnace and allowed tocool while still in the jig.

The carbonaceous residue was removed by placing the sheet in a suitablereflux assembly containing nitric acid, and refluxing at the boilingpoint of the acid until the characteristic white color of thepolyfluorocarbon resin developed.

The sample was neutralized by dilute ammonia, washed in deionized water,and pressed dry between paper towels. On test the specific gravity ofthe sample was 2.2.

MODIFICATIONS OF THE GENERAL STEPS OF THE PROCESS In addition to thechanges in properties of the final duplicate product which can beproduced by variation of the sintering and carbonization conditions,other modifications or variations of the above described process can bemade to produce a variety of other properties in the final duplicateplastic product.

For example the duplicate plastic product can be made stronger or softeror receive a colored decorative pattern, have its texture altered ortake on certain electrical properties or ion exchange properties, etc.

A representative sampling of the potential areas of modification willnow be described.

A. Modifying or Treating the Matrix before the lmpregnating step.

Since the above described process except for dimensions makes asubstantially identical duplicate of the matrix, the initial conditionof the matrix will have bearing on the ultimate product obtained.

Conversely, where it is desired to produce an ultimate product withcertain given properties then one way of obtaining these properties willbe to initially invest the matrix to be duplicated with such property ina manner which will permit this property to be transferred over to theduplicate.

Relatively simple modifications of the above de scribed processaccomplishing these results are now illustrated:

EXAMPLE Direct treatment of the Matrix Acid Hardening CorrespondingPlastic Duplicate In order to obtain a hard finish, a piece ofconventional paper stock was acid hardened.

This hardened piece of conventional paper stock was used as the matrixin the procedures outlined in Example 4.

The product obtained was plastic duplicate of the initial matrixhardened in the same manner.

EXAMPLE 6 Direct treatment of Matrix Partial Hydrolysis CorrespondingPlastic Duplicate A piece of conventional paper stock was partiallyhydrolyzed to give it a soft texture and the treated paper was used asthe matrix in the procedures outlined in Example 4.

The product obtained was a rather soft plastic duplicate equivalent tothe texture of the initially treated matrix.

B. Pre-impregnating or Two Stage impregnation of the Matrix(Incompatable Duplicating substances).

Probably the most versatile means for altering the properties of thefinal product is to add a preimpregnating step or conduct theimpregnation in two or more steps to develop a certain property such asgiving the final product conductive properties, or adding filler toincrease the opacity of the final product.

Pre-impregnation of two-stage impregnation is relied on where theimpregnating substances are not compatable or where it is necessary toobtain some desirable result such as the printing ofa pattern on theplastic duplicate.

EXAMPLE7 Conductive Polyfluorocarbon Resin Duplicate from a Matrix ofTissue Paper A one normal solution ofa decomposable metal compound Fe Clwas prepared and a weighed sample of the tissue paper was dipped andsaturated with the solution.

The pre-impregnated tissue paper sample was exposed to NH CI-I to changethe ferric salt to the ferric hydroxide in accordance with the equation.

2 Fe on mo an o 2 Fe O 3c Fe 3C0 When the oxide is reduced, the oxygenand heat are increased to carbonize the tissue paper sample.

Similarly, in the oxidation-reduction step with H 0 where the ironelement will be oxidized to ferric oxide according to the equation:

it is necessary to reduce the ferrous oxide back in a Hydrogen orreducing atmosphere, as follows:

In this modification of the general steps of the process the productobtained had a gray color. A current of electricity passed from one endof the sheet to the other as measured with probes from a currentcarrying circuit and a galvanometer.

EXAMPLE 8 Polyfluorocarbon Resin Duplicate with Filler to IncreaseOpacity I. A 20 percent by volume polytetrafluoroethylene dispersion isprepared as in Example 1. 2. Titanium tetrachloride solution percent ispoured into an argonpurged open vessel. 3. A steam vapon'ser isactivated. Dip a piece of acid resistant filter paper into the TlCLsolution. Allow excess to drip off and then expose both surfaces to thesteam of the vaporiser for minutes on each surface. Wash paper in diluteammonia, then distilled water until no chloride (as detected by silvernitrate) is present and dry in an oven at 150F. for one hour.

Dip titania impregnated paper in the polytetrafluoroethylene dispersion,let dry at room temperature or at 150F. for 30 minutes. Sinter a 670F.for minutes in the forced air one pass oven between stainless steelscreens as in Example 4.

Place material, after cooling to room temperature, in a reflux assemblycontaining 30-35 percent hydrogen peroxide and 2 percent Triton X 100.Reflux at 6080 C. for 24 hours or until the characteristic whitepolytetrafluoroethylene color is obtained.

EXAMPLE 9 Polyfluorocarbon Resi Duplicate of a Matrix Having a FluffyTexture.

l. A percent by volume polyfluorocarbon resin dispersion of TEE (DupontT.M.) is prepared as in Example 1.

2. An Amino-Triazole solution 15 percent is prepared.

A piece of conventional cotton cloth was dipped in the Amino-Triazolesolution and after it was removed the excess was allowed to drip off.

The pre-impregnated cloth was then allowed to air dry.

The dried pre-impregnated cloth was then sprayed until saturated with 20percent Teflon 30 solution contains 2 percent wetting agent and was putthru all the procedures set forth in Example 1.

As a result of the outgassing of nitrogen previously, the duplicatedplastic product had a fluffy somewhat cottony texture.

EXAMPLE l0 Selective Pre-impregnation to Form a Pattern on thePolyfluorocarbon Resin Duplicate A piece of conventional paper wasselected which was capable of being wetted or impregnated withoutrunning by the vehicle in which the coloring material is suspended.

Acqueous suspensions of graphite which yields a gray to black effect;chrome oxide which yields light to dark green effect and iron oxidewhich yields a brown to black effect were prepared in variousconcentrations between 2 to 10 percent by weight. These pigmentsfamiliar to the decorative arts industries are readily available on theopen market, are thermally stable at the sintering temperatures andresist selective oxidizers used during the oxidation-reduction step ofthe process.

The acqueous suspensions of the respective dyes were applied by dippinga stamping member in the pigment and then stamping the paper in apredetermined color decorative pattern.

The paper was oven dried at 150F to remove the solvent in which thepigments were suspended.

The printed paper was now passed thru the steps of the process asoutlined in Example 4.

The plastic duplicate obtained had a specific gravity of 2.2 and had theprinted pattern found therein throughout the discrete fibers as in theoriginal paper matrix duplicated.

The crux of this type of selective pre-impregnated or the formation ofprinted plastic material is to select pigmenting materials which aremore stable to the oxidizing agents used then the carbon residue of thefiber geometry of the matrix.

Prolonged oxidation is to be avoided. However if the background of theplastic has a yellow cast refluxing the plastic duplicate with thepattern can be done up to two hours in a 5 percent hypochlorous acidsolution to bleach out the plastic if care is taken to avoid oxidizingout the printed pattern by over bleaching.

EXAMPLE 11 Multiple Polyfluorocarbon Resin Duplicate of a Matrix ofcommercial tissue paper A sheet of commercial tissue paper (KimberlyClarks Kemwipes) was saturated by a 10 percent by weight of a finelydivided organic suspension of polynonochlortrifluoroethylene and thetissue paper with this first impregnation of plastic material wasthoroughly air dried for 8 hours.

The tissue paper with the first impregnation was then put through allthe steps set forth in Example 4 above.

On the test the specific gravity of the sample was 2.2 and the samplewas stronger and more resilient in texture than the plastic duplicateformed by the single impregnation step of Example 4.

c. One stage impregnation of the matrix with more than one duplicatingsubstance.

Another convenient technique for producing or altering the properties ofthe final product obtained in accordance with the general steps of theprocess above described is to co-deposit duplicating substances whichare compatable with each other.

EXAMPLE l2 Silicon Dioxide (SiO Polytetrafluoroethylene Dispersions TheSiO is added to the polyfluorocarbon resin dispersion as a dry powder 29to 50 percent by weight was mixed thoroughly with the dispersion and themixture was applied as set forth in the impregnating steps of Ex amplesl, 2 and 4 above.

The product obtained with a silica filled plastic duplicate with aspecific gravity of 2.1.

EXAMPLE 13 Titanium Dioxide (TiO Polytetrafluoroethylene dispersion TheTiO is added to the polyfluorocarbon resin dispersion as a dry powder 5to 25 percent, by weight was mixed thoroughly with the dispersion andthe mixture was applied as set forth in the impregnating steps ofExamples l, 2 and 4 above.

The product obtained was a titania filled plastic duplicate with aspecific gravity of 3.1.

EXAMPLE l4 Nickel Carbonyl Powder and Polytetrafluoroethylene DispersionThe nickel carbonyl Powder having a particle size not greater than 0.2microns is added to the polyfluorocarbon resin dispersion as a dry agent5 to 25 percent by weight was mixed thoroughly with the dispersion andthe dispersion mixture was applied as set forth in the impregnatingsteps of Examples 1, 2 and 4 above.

The product obtained was a nickel filled plastic duplicate with aspecific gravity of 3.4 which was highly conductive from end to end whentested.

Similar products made with Iron Carbonyl and Platinum powders producedthe same type products and results.

EXAMPLE l Multiple Polyfluorocarbon Resins Duplicate Of a Matrix ofCommercial Tissue Paper A sheet of commercial tissue paper (KimberlyClarks Kemwipes) was saturated in acqueous solutions consisting of amixture of the following:

a. percent by weight polytetrafluoroethylene with 1 percent Triton X100.

b. percent by weight of polyparfluorinated ethylene propylene copolyrnerwith 2 percent Triton X 100 Thereafter the impregnated tissue paper wastaken through all the same steps set forth in Example 4 above.

The product obtained was a plastic duplicate of the original tissuepaper with specific gravity of 2.2. The product as in the case ofExample I 1 was stronger than the plastic duplicate obtained by thesingle duplicating substance used in Example 4.

cl. Modifying the Process to strengthen the Final Product One way tostrengthen the final product obtained by the general steps of theprocess is to increase the sintering temperature and time or theoxidation rate as this will increase coalescence and reduce porosity ofthe final duplicate plastic product obtained.

Still another method is to reimpregnate the sintered plastic duplicatewith additional duplicating substance either before or after theoxidation-reduction step of the general steps of the process abovedescribed.

EXAMPLE 16 Prestressing to Strengthen the Polyfluorocarbon ResinDuplicate All the steps of Example 2 were followed up to the completionof the sintering and carbonization procedures.

Thereafter, the sintered plastic duplicate is removed from the sinteringfurnace and immediately plunged into a cold water bath maintained atabout 32F until the temperature of the plastic duplicate drops below thetransition temperature at 621F.

The prestressed plastic duplicate was then taken through the remainingsteps as set forth in Example 2 to provide the final plastic duplicateproduct.

This product has a 2.2 specific gravity and had a tougher and moreresilient texture than the plastic duplicate obtained by the steps setforth in Example 2.

EXAMPLE 17 Annealing Technique All the steps of Example 2 were followedup to the completion of the sintering and carbonization procedures.

Thereafter the temperature in the sintering furnace was permitted toreduce at the rate of 1F per minute until a temperature of 500F waspassed.

The annealed plastic duplicate was then taken through the remainingsteps as set forth in Example 2 to provide the final duplicate plasticproduct.

This product as Example 16 was stiffer and less resilient than theplastic duplicate obtained by the steps set forth in Example 2. Thespecific gravity was 2.2.

EXAMPLE l8 Redipping the Polyfluorocarbon Resin to Strengthen it.

All the steps of Example 2 were followed.

The final plastic duplicate was then redipped in the 30 percent byvolume colloidal dispersion of polyfluorocarbon resin 4IBX (Dupont T.M.)and TFE 30" (Dupont T.M.) containing 4 percent Triton X wetting agent;and air dried for two hours.

The dried redipped plastic duplicate was then placed in a sinteringfurnace and resintered at 670F for a relatively short period of timeabout 12 minutes, an extra shrinkage will occur the longer the productis maintained at the sintering temperature.

The product obtained was measurably tougher and more resilient than thecorresponding single dipped plastic duplicate made by the steps ofExample 2.

Note that redipping can also be effected before oxidation butresintering will have to be effected at 725F in the presence of oxygenand the time period controlled to prevent undue shrinkage.

e. Modifying the Process to Post Coat with resinter- It is possible togive the final duplicate plastic product different properties bypost-coating the product.

EXAMPLE I9 Polyfluorocarbon Resin Duplicate with a BacteriocidalCoating.

All the steps of Example 4 were followed and the final plastic duplicateobtained.

Then the finished plastic duplicate was redipped in a bacteriocidalagent, mercurochrome, and the product dried.

EXAMPLE 2O Polyfluorocarbon Resin Duplicate with lon Exchange Coating.

All the steps of Example 1 were followed and the final plastic duplicatesheet material was obtained.

Thereafter the plastic duplicate bed sheet was dipped into an ionexchange resin solution of a sulphonic acid derivative of polyetyreneand the product was air dried.

The bed sheet was cut up into shapes which permitted the material to besubstituted in conventional apparatus using ion exchange membranes andthe product produced improved results over that of correspondingmaterials now used. GENERAL COMMENTS AND FACTS REGARDING THE PROCESS:PREIMPREGNATION, SINGLE STAGE IMPREGNATION WITH CO-DEPOSITING ORMULTl-STAGE IMPREGNATION It is believed clear that impregnation can bevaried at will and that compatable and incompatable substances of thecorrect particle size can be deposited during the impregnation step toobtain the desired property.

The general condition required is that where noncompatable substancesare deposited separately the matrix should be dried between eachdepositing step.

Any number of impregnation steps therefore can be undertaken. Forexample, a titanium filled printed plastic duplicate can be obtained asby combining Examples 8 and I0.

Further as will appear clear hereinafter the modified impregnation stepscan be correlated with post treating steps to produce other desirableresults.

It should be noted that where the duplicating substances are varyingforms of polyfluorocarbon that whether they are compatable or not theycan be deposited on the matrix with respect to each other in all ratiosof l to 100 percent by weight.

Further where a multiple selection of polyfluorocarbon resins aredeposited the matrix for all purposes is treated as if only a singleresin has been deposited as the highest sintering temperature for therespective polyfluorocarbon resins deposited will control the sinteringtemperature at which the matrix is held.

Microscopic inspection of the final product duplicate in all of theexamples show that they are substantial duplicates in all respect to theoriginal fibers of the matrix.

The effect of redipping and resintering on pore size is illustrated bythe following data.

1. Using a Whatman No. 1-47mm disk of filter paper as the matrixrespectively; three plastic duplicate filters were made. Sample PA hadone impregnation. Sample PB had one impregnation and one redip. SamplePC had one impregnation and two redips. 2. Test data on these sampleswere obtained as follows:

FLOW TIME Whatman N0. 4 Filter-47 mm Disk 500 cc H2 sec. Sample PAFilter-47 mm D isk 500 cc H 16 sec. Sample PB Filter-47 mm Disk 500 cc H0 34 Sample PC Filter-47 mm Disk 500 cc H2 0 335 sec.

Tests would further appear to indicate that where filter paper is thematrix the porosity of the plastic duplicate made in accordance withExample 4, a one impregnation procedure, will be reduced approximately40 percent of the porosity of the original matrix.

Porosity is believed to be closely related to shrinkage and therefore itis desirable during the process to prevent the dried impregnated matrixfrom going its own way during the sintering and carbonization steps asby the use of a frame or by keeping the matrix under some tension as isdone in the apparatus for performing the general steps of the processwhich apparatus will now be described.

Where the duplicating substance sinters or coalesces below the thermaldecomposition point for the matrix to be duplicated then the presentprocess must be modified in the steps which rely on the relation of thematrix and the duplicating substance, thus pre-sintering and hydrolizingin a temperature controlled medium acts to coalesce the duplicatingsubstance and simultaneously destroys or eliminates the matrix in amanner similar to the relationship established by sintering andcarbonization.

APPARATUS FOR CONTINUOUS OPERATIONS OF PROCESS Referring further to thedrawings, FIG. 10 shows an apparatus for performing the process of thepresent invention in a continuous manner.

Thus there is shown at l a Matrix in the form of a roll of materiali.e., paper, textile fabric, cellulose sheeting, viscose sponge, fabric,regenerated rayon cloth etc, which has sufficient strength to travelpreferably unsupported through the various steps of the process and ismaintained under suitable tension by any suitable means.

The Matrix is passed over rollers 2 and 2b, into a tank 3 which containsa collodial dispersion having the concentration and particle size andwetting agent for this particular Matrix. In the tank 3, the colloidaldispension may be agitated as by a mixing member 4 so as to deposit thecolloidal dispersion as thoroughly and homogeneously as possible on theMatrix as it passes through the tank 3.

As shown, the Matrix l is disposed in the tank to pass over rollers 5a,5b and 5c so that it can make at least two passes through the collodialdispension. It is believed clear that if additional passes are neededthat the tank 3 can be expanded and the number of rollers increased toaccomplish this result.

Matrix 1 now impregnated with colloid and the continuous phase of thecolloidal dispersion from its pass through the colloidal dispension intank 3 moves over roller 6 into a low heat drying oven 7 where a gentlebaking heat of F. acts to evaporate the water present in the impregnatedMatrix and leaves the discontinuous particle stage of the presentinvention on the Matrix.

Next, the dried impregnated Matrix 1 passes through a heat furnace 8between 350-500F. where the wetting agent is removed more rapidly andcarbonization of the Matrix is commenced.

After passing from furnace 8, the dried impregnated Matrix 1 with thecolloid still in discrete particles thereon is then sent into asintering furnace 9 at 625F to 900F where the combined steps ofsintering and carbonization occur to simultaneously coalesce thediscrete particles of colloid in the fibers of the Matrix into acontinuous self-supporting duplicate of the fiber geometry of the Matrixand to oxidize by controlled combustion the fibers of the Matrix.

Parts 10a and 10b coacts with a fan 11 and damper 12 as illustrateddiagrammatically to control the recirculation of air in the sinteringfurnace 9 whereby the desired rate of combustion will be effected.

At some point in the sintering furnace 9 the Matrix 1 decomposes and theduplicating substance forms into continuous unitary duplicate thereof inwhich the carbonaceous residue of the fiber geometry of the Matrix ishomogeneously disposed so that as it passes from the sintering furnace 9it will have a characteristic blackened or charred appearance.

The sintered duplicate CD is now passed from the sintering furnace 9over the roller 13 into an oxidizing chamber 14 where any suitableoxidation-reduction procedure can be performed which acts to remove thedeposited carbon residue from the sintered plastic duplicate.

For example, boiling solution of one normal I-INO can be used for thispurpose or even hot air at elevated temperatures will accomplish thisresult.

In the illustrated embodiment of the apparatus, the sintered plasticduplicate CD is passed into a suitable oxidation solution over rollers15a, 15b, 15c and 15d to permit it to make several passes into thisoxidation medium.

From the oxidation chamber 14 the treated plastic duplicate CD is pastover roller 16 into a washing and neutralizing tank 17, then over roller18 into a drying oven 19 at about 300F.

From the drying oven the final duplicate plastic sheet is passed over aroller 19 and wound on a suitable storing rod 20 for its eventualshipment and use.

It is believed clear from the process steps and the apparatus forperforming the process as above described that a multitude of matricescan be reproduced by the present process in an extremely wide range fromtissue paper to a complex suit of clothes to any articles, object orgoods, in materials having the properties which adapt it for thenecessary relationship with the duplicating substance selected.

Conversely the myraid of duplicating substance will provide a multitudeof new and unusual products, particularly plastic products adapted notonly tofunction and obtain results similar but superior to those of thematrix from which they have been duplicated but further offer a varietyof new products which have been long sought after by many industries butnot yet achieved because of the limitation in the technical advancesrelative new plastic materials on the market.

Therefore although this invention and a variety of modified formsthereof have been described and illustrated by reference to certainspecific examples and various expressions or terms of description havebeen utilized herein in an effort to set forth the invention clearly,such illustrated examples or terms of description are not intended to beby way of limitation or to exclude any equivalents of the features shownand described; and it is realized that numerous modifications arepossible within the scope of the invention as now claimed.

What is claimed is:

11. A plastic material, article, or object formed as a substantialduplicate in high molecular weight polymeric material selected from thegroup consisting of polyfluorocarbon resins, polyvinyl chloride andpolyvinylidene chloride of a matrix of fiber materials by the processof:

selecting the matrix to be duplicated from the group consisting offibrous cellulosic and proteinacious material which will Carbonize;

impregnating the matrix by randomly depositing on and along the discretefibers of the matrix finely divided particles of at least oneduplicating substance of high molecular weight polymeric materialsselected from the group consisting of polyfluorocarbon resins,polyvinylchloride and polyvinylidene chloride having a sinteringtemperature at the carbonizing temperature for the particular fiberstructure of the matrix selected;

subjecting the impregnated matrix to an elevated temperature less thanthe ignition temperature for the fibers of the matrix in an atmospherehaving oxygen present to oxidize the fibers into carbona ceous form,

maintaining continuous oxidation at the elevated temperature of thecarbonized fibers with sufficient oxygen present that the temperatureconditions along the carbonized fibers will at least equal the sinteringtemperature of the duplicating substance and will cause the discreteparticles of the duplicating substance deposited thereon to align andorient along the carbonized fibers of the matrix; controlling theconcentration of oxygen present during said continuous oxidation of thecarbonized fi bers of the matrix at the elevated temperature to limitand regulate the rate of oxidation and elimination of the carbonizedfiber structure and the decrease in mass of the matrix whereby thealigned and oriented particles of the duplicating substance of thesintering temperature along the carbonized fibers will gradually replacethe carbonized fibers as they are eliminated under the controlledoxidation conditions and will coalesce to form a selfsupportingcontinuous duplicate in the duplicating substance of the fiber structureof the matrix, and separating the residue of carbonaceous ash of thefiber structure of the matrix from the substantial duplicate thus formedto provide the finished plastic material, article or object.

2. The plastic material, article or object of claim 1 formed from aplurality of the said high molecular weight polymeric materials at leastone of which is a polyfluorocarbon resin.

3. The plastic material, article or object of claim 1 including:

materials combined with at least one of said high molecular weightpolymeric materials selected from the group consisting of silica andtitania to increase the opaqueness of the plastic material, article orobject.

4. The plastic material, article or object of claim 1 including:

materials combined with at least one of the said high molecular weightpolymeric materials selected from the group consisting of metal carbonylcompounds and pure metal powders to increase the conductive propertiesof the plastic material, article or object.

5. The plastic material, article or object of claim 1 wherein thesubstantial duplicate is coated with a bactericidal agent afterduplication of the matrix is completed.

6. The plastic material, article or object of claim 1 wherein thesubstantial duplicate is coated with an ion exchange resin materialafter the substantial duplicate of the matrix is fully formed.

7. The plastic material, article, or object of claim 6 wherein the ionexchange resin coating material is a non-ionic substance from the classof sulphonic acid derivatives of polystyrene.

2. The plastic material, article or object of claim 1 formed from aplurality of the said high molecular weight polymeric materials at leastone of which is a polyfluorocarbon resin.
 3. The plastic material,article or object of claim 1 including: materials combined with at leastone of said high molecular weight polymeric materials selected from thegroup consisting of silica and titania to increase the opaqueness of theplastic material, article or object.
 4. The plastic material, article orobject of claim 1 including: matErials combined with at least one of thesaid high molecular weight polymeric materials selected from the groupconsisting of metal carbonyl compounds and pure metal powders toincrease the conductive properties of the plastic material, article orobject.
 5. The plastic material, article or object of claim 1 whereinthe substantial duplicate is coated with a bactericidal agent afterduplication of the matrix is completed.
 6. The plastic material, articleor object of claim 1 wherein the substantial duplicate is coated with anion exchange resin material after the substantial duplicate of thematrix is fully formed.
 7. The plastic material, article, or object ofclaim 6 wherein the ion exchange resin coating material is a non-ionicsubstance from the class of sulphonic acid derivatives of polystyrene.